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Understanding DVB-T Setup

Added by s kemp almost 14 years ago

Hi,
I have 2 Hauppauge Nova-T PCI DVB-T tuner cards in a Ubuntu 10.10 box. I have the card working perfectly using MythTV as a backend and MythTV as a frontend. However I was looking to use XBMC as my frontend of choice (due to better integration of iPlayer for us in the UK). I have set up TV headend correctly, I beleive, and have configured the two connexant based cards with my local DVB-T 'freeview' network (UK, Crystal Palace). Once the cards have done an initial scan of the Muxes (six in total) the summary reports that 103 services are available.

Once I start the mapping process the system works through the various mappings and I end up with approximately 40 channels 'mapped'. I can see these channels in the XBMC front end and am able to watch them as expected. The only issue here is that the channels are in a pretty random order (but i will look into that once i have them all present!).

I am a little unclear as to what exactly some of the terminology means and if it means what I believe it to then I am missing some 60 channels. When the system reports that it has 103 services does it mean that it has successfully tuned 103 services on the tuner card? If so what happens in the mapping process? does it attempt to map a long list of channel data (from where?) to each of those it has found on the muxes and when a match is found it will map the channel. Or is it saying that there are a possible 103 services known to exist on the mux but i only get 40 of them (this is not true, but I wonder if the issue is with the tuning).

Assuming that the issue is that the system is having trouble in matching the 103 channels it has found to data about the channels how do I go about improving the match? where does the list of channels get populated from?

I am sorry if this is so obvious as to be annoying to have to answer, but it has been driving me mad in trying to work out what is happening. I really love the interface and the relative ease in which it works and can't wait to have a fully working setup!
Many thanks


Replies (2)

RE: Understanding DVB-T Setup - Added by Andreas Smas almost 14 years ago

I'll try to clarify this a bit

A service in Tvheadend lingo is a channel but on the "input" side of Tvheadend. A service is not restricted to a TV channel but can rather be:

  • A normal TV channel (as you would perceive it as an end-user)
  • A radio channel
  • A data stream (for firmware upgrades to SetTop boxes)

A service can also originate from IPTV or Analogue video (V4L)

And a channel in Tvheadned lingo is a channel on the "output" side. I.E. what you subscribe to when watching a live channel or what the recorder will try to record from.

A channel can be comprised of multiple services.

When you press the 'map service to channels' button, Tvheadend will try to decode TV on all services available on the DVB adapter. If it manage receive a complete video frame it will classify the service as a working TV channel and create a channel with that name (if a channel with that name already exist, it will just reuse that) and map that service to the channel.

When something (live TV or a record) subscribes to a channel, Tvheadend will find the best available service for that channel that is available. The services are prioritised depending on from what the originate, as follows:

  1. Unscrambled DVB/ATSC
  2. IPTV
  3. Scrambled DVB/ATSC
  4. Video4Linux (Analogue input)

RE: Understanding DVB-T Setup - Added by renne - over 13 years ago

Does that mean TVHeadEnd falls back to a DVB-T-tuner if a DVB-S2-tuner fails in case they provide the same channel?

    (1-2/2)